Record head actuator sandwiched damper plus travel limiter

ABSTRACT

A magnetic recording head positioning assembly includes a coarse travel carriage secured to and spaced away from each of a front end assembly and head assembly via sandwiched fine guiding flexures and isolation flexures. The fine guiding flexures permit relative movement between the coarse travel carriage and head assembly. The isolation flexures permit relative movement between the coarse travel carriage and front end assembly. The fine guiding and isolation flexures thus isolate the coarse travel carriage from the front end assembly and head assembly. The assembly further includes dampers sandwiched between the coarse travel carriage and isolation flexures to limit movement of the isolation flexures.

BENEFIT CLAIM; INCORPORATION BY REFERENCE

This application claims priority as a continuation of U.S.Non-Provisional application Ser. No. 15/411,130, filed on Jan. 20, 2017,now U.S. Pat. No. 9,805,751, to be issued on Oct. 31, 2017, which ishereby incorporated by reference.

TECHNICAL FIELD

This disclosure relates to head actuators that are used to positionrecording heads in data storage tape drives.

BACKGROUND

Head actuators are used to move a recording head relative to a recordingmedia. This recording head motion allows servo readers and read/writeelements on the head to be aligned correctly to the media during trackfollowing read/write operations.

Typically, recording head positioning requirements are high bandwidth.That is, head position changes required to keep the head in the correctlocation on the media must be made quickly and accurately. There are anumber of variables that are considered in the design of recording headactuators in order to maintain high bandwidth head positioning. One ofthese is the actuator's response to input frequencies. Out-of-planeresonances in the moving head can create dynamic instabilities thatreduce the bandwidth of the head actuator. The result is a tape drivethat does not meet its performance requirements.

SUMMARY

A recording head actuator may be configured such that its bodies of massare isolated to better tune the frequency response to certainoperational and impact events. Flexures, which in some examples arethin, band-like plates used to connect isolated bodies of mass, canfacilitate such isolation. Here, parallel sets of flexures are used toisolate bodies of mass associated with coarse travel head adjustment andfine travel head adjustment. This dual isolation can improve recordinghead performance in the presence of vibration and offer increasedprotection to shock and handling events.

In one embodiment, a magnetic recording head positioning assemblyincludes a front end assembly, a head assembly, and a coarse travelcarriage spaced away from the front end and head assemblies. The frontend assembly includes an isolation mount and a voice coil motor housingand coil assembly. The head assembly includes a fine travel carriage,head carrier, and recording head. Fine guiding flexures are secured tothe coarse travel carriage and head assembly to permit relative movementbetween the coarse travel carriage and head assembly. And, isolationflexures are sandwiched between the fine guiding flexures and secured tothe coarse travel carriage and front end assembly to permit relativemovement between the coarse travel carriage and front end assembly.

In another embodiment, a coarse adjustment subassembly for a magneticrecording head positioning assembly includes an isolation mount, a voicecoil motor housing and coil assembly secured to the isolation mount toform a front end assembly, and a coarse travel carriage spaced away fromthe front end assembly. One or more isolation flexures are secured tothe coarse travel carriage and front end assembly to permit relativemovement between the coarse travel carriage and front end assembly. And,one or more dampers are disposed between and compressed by the coarsetravel carriage and the isolation flexures to limit travel of theisolation flexures.

In yet another embodiment, a magnetic recording head positioningassembly includes a coarse travel carriage secured to and spaced awayfrom each of a front end assembly and head assembly via sandwiched fineguiding flexures and isolation flexures. This arrangement is such thatthe fine guiding flexures permit relative movement between the coarsetravel carriage and head assembly, and the isolation flexures permitrelative movement between the coarse travel carriage and front endassembly to isolate the coarse travel carriage from the front endassembly and head assembly. Dampers are sandwiched between the coarsetravel carriage and isolation flexures to limit movement of theisolation flexures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a coarse adjustment subassembly for amagnetic recording head positioning assembly.

FIG. 2 is a perspective view of a magnetic recording head positioningassembly.

FIG. 3 is a side view, in cross-section, of the magnetic recording headpositioning assembly of FIG. 2.

DETAILED DESCRIPTION

Various embodiments of the present disclosure are described herein.However, the disclosed embodiments are merely exemplary and otherembodiments may take various and alternative forms that are notexplicitly illustrated or described. The figures are not necessarily toscale; some features may be exaggerated or minimized to show details ofparticular components. Therefore, specific structural and functionaldetails disclosed herein are not to be interpreted as limiting, butmerely as a representative basis for teaching one of ordinary skill inthe art to variously employ the present invention. As those of ordinaryskill in the art will understand, various features illustrated anddescribed with reference to any one of the figures may be combined withfeatures illustrated in one or more other figures to produce embodimentsthat are not explicitly illustrated or described. The combinations offeatures illustrated provide representative embodiments for typicalapplications. However, various combinations and modifications of thefeatures consistent with the teachings of this disclosure may be desiredfor particular applications or implementations.

One method practiced today for reducing out-of-plane resonances inrecording head actuators is to isolate significant bodies of massinherent in the actuator from the actuated mass of the moving recordinghead. Isolating these mass bodies from the moving head works to minimizetheir effect on the frequency response of the actuated head by reducingthe occurrence of out-of-plane resonances in the head. One conventionalmethod for isolating bodies of mass in actuator design is to useisolation flexures. Flexure isolation can be an effective method of massisolation and frequency response improvement but its implementation canbe problematic. Two inherent problems with implementing flexureisolation into actuator design are that 1) flexure isolated masses havetheir own resonant frequencies that can show up and degrade thefrequency response of the actuated head and 2) flexure isolated systemsare susceptible to damage when exposed to shock and handling events thatforce the flexures to bend beyond their travel limits. Shock events thatmight damage isolation flexures can occur during product shipping.Flexure damage due to rough handling can occur during the manufacturingprocess.

The first problem of flexure isolated masses having their own resonantfrequencies is addressed by conventional methods, one of which includesadding dampers to the actuator design to damp out resonant frequenciesbefore they can get into the actuated head. The second problem offlexure isolated systems being susceptible to damage when exposed toshock and handling events is not addressed today and is the problembeing addressed here.

Recording head actuator sandwiched dampers plus travel limitersdisclosed here address situations in which flexure isolated systems aresusceptible to bending damage when exposed to shock and handling events.Certain embodiments may incorporate components that are sandwichedbetween the moving isolation flexures and static surfaces within thehead actuator assembly. These new damping plus travel limitingcomponents may perform a dual function. First, they may be made out ofenergy dissipative materials (e.g., foam, etc.) that remove energy fromthe moving isolation flexures and therefore damp out isolation flexuremotion. This reduces the likelihood that the flexure isolated massresonant frequencies will negatively impact the frequency response ofthe moving head. Second, these new sandwiched components may becomestiffer as they are compressed between the isolation flexures and staticsurfaces of the head actuator. This stiffening response to compressionreduces the amount of isolation flexure travel that can occur duringshock and handling events which in turn reduces the likelihood that theflexure isolated system will be damaged by bending during shipping andhandling.

Referring to the embodiment of FIG. 1, a coarse adjustment subassembly10 of a magnetic recording head positioning assembly (FIGS. 2 and 3)includes a coarse travel carriage 12, an isolation mount 14, a voicecoil motor housing and coil assembly 16, isolation flexures 18, anddampers 20. The mount 14 defines a cupped region 22, having bores 24,configured to receive the assembly 16. Fasteners 26 secure the mount 14and assembly 16 together such that they move together as a single frontend assembly unit. The mount 14 also defines a pair of legs 28 thatextend away from the region 22 to form a support to which the carriage12 is attached via the flexures 18 as described further below.

The carriage 12 defines a mounting region 30 configured to be arrangedadjacent to and spaced away from the legs 28 such that the carriage 12and mount 14 are spaced away from each other. The region 30 includes twopair of opposing platforms 32 that provide mounting surfaces for thedampers 20. Each pair corresponds to one of the legs 28. And the dampers20, relative to the legs 28, are situated near opposite ends. The legs28 and platforms 32 thus define partial cavities within which thedampers 20 are disposed.

The flexures 18, which are U-shaped in this example, are positioned atopposite ends of the legs 28. A base 34 of each of the flexures 18extends between the legs 28, and arms 36 of each of the flexures 18extend to the region 30 and over the dampers 20 such that the dampers 20are sandwiched between the platforms 32 and arms 36. Fasteners 38 securethe bases 34 to the legs 28 and the arms 36 to the region 30 to therebycompress the dampers 20 between the platforms 32 and arms 36. Unlikeprevious arrangements in which the carriage 12 and assembly 16 arerigidly mounted together, here the carriage 12 and front end assemblyformed by the mount 14 and assembly 16 can move relative to one anothervia flexing of the flexures 18. Further, cyclic flexing of the flexures18 is damped by the compressed dampers 20. The flexures 18 and dampers20 thus act to isolate the carriage 12 from the mount 14.

Referring to FIGS. 2 and 3, the subassembly 10 is shown within thecontext of a magnetic recording head positioning assembly 40. Other thanthe components of the subassembly 10, the assembly 40 includes a finetravel carriage 42, a head carrier 44, a recording head 46, fine guidingflexures 47, a coarse actuation motor 48, a coarse actuation motor mount50, and a coarse guiding shaft 52. Additional conventional componentsare also shown. They, however, are not necessarily labelled orexplicitly mentioned for the sake of discussion clarity.

The carriage 42 is disposed between the legs 28 and extends from theassembly 16 through an opening 54 in the region 22. The carrier 44 isbonded to the carriage 42, and the head is attached to the carrier 44such that the carriage 42, carrier 44, and head 46 move together as asingle unit. A screw 56 clamping magnets 57 of the assembly 16, andengaged with the carriage 42 facilitates movement of the carriage 42(and carrier 44 and head 46) relative to the mount 14. Operation of theassembly 16 causes the magnets 57, which may move relative to theassembly 16, and screw 56 to move the carriage 42 closer to or furtheraway from a housing of the assembly 16 in the axial direction of thescrew 56.

The flexures 47, which are rectangular shaped in this example, arepositioned near opposite ends of the carriage 42, and span between thecarriage 42 and mounting platforms 58 of the region 30 such that theflexures 47 sandwich the flexures 18 and dampers 20 therebetween.Fasteners 60 secure the flexures 47 to the carriage 42 and platforms 58to permit relative movement between the carriage 12 and carriage 42 (andcarrier 44 and head 46). The flexures 47 thus act to isolate thecarriage 12 from the carriage 42 (and carrier 44 and head 46), and toguide the head 46 relative to recording media (not shown) in a datastorage tape drive.

Because the flexures 18 and dampers 20 are nested between the flexures47, the head 46 is thus provided with dual (or parallel) isolationprotection. To the extent the mount 14, assembly 16, carriage 42,carrier 44, and head 46 move together during coarse travel adjustment,these components are isolated from the carriage 12 via the flexures 18and dampers 20. To the extent the carriage 42, carrier 44, and head 46move together during fine travel adjustment, these components areisolated from the carriage 12 via the flexures 47.

The motor 48, mount 50, and coarse guiding shaft 52 facilitate movementof the carriage 12. The shaft 52 is slidably mounted to the mount 50 viaguide bushings. And, the carriage 12 is fixedly mounted to the shaft 52.A spring loaded lead screw 62 extending from within the motor 48 andthrough the mount 50 is engaged with carriage 12. Operation of the motor48 causes elements therein to rotate in clock-wise or counter-clock-wisedirections relative to the screw 62 to move the carriage 12 closer to orfurther away from the motor 48 and relative to the mount 50.

Equal and opposite forces exist between the housing of the assembly 16and the screw 56 and magnets 57. Forces drive assembly 16 when the head46 is actuated to follow movements of a recording media. This can feedenergy into the mount 50, via the carriage 12, and energy into the head46 because the carriage 42, carrier 44, and head 46 all ride on thecarriage 12 and mount 50. Isolating the carriage 12 from the assembly 16via the flexures 18 as described reduces the amount of energy that canbe fed back into the carriage 12 and mount 50, which in turn improvesthe frequency response of the head 46. As such, the damper/flexurearrangements contemplated herein make the assembly 40 more robustagainst shock and handling events for the reasons explained above.

While example embodiments are described above, it is not intended thatthese embodiments describe all possible forms encompassed by the claims.The carriage 12, mount 14, assembly 16, carriage 42, etc., for example,are shown to take particular forms. These forms, however, largely dependon the specific application and environment, and may be different. Thecarriage 12 need not include platforms 32. Recessed areas in anotherwise solid wall may suffice. The mount 14 need not define a pair oflegs. A single pedestal may also be used. Moreover, movement of thecarriages 12, 42 may of course be facilitated by motors or apparatusother than that described.

The flexures 47 are shown to sandwich the flexures 18. Theother-way-round is also possible. The carriage 12 and mount 14 (ifpresent) may be configured such that mounting surfaces for the flexures18 are outside those for the flexures 47. In this arrangement, theflexures 47 are nested within the flexures 18. Use of a single flexure18 (as opposed to a pair) is also possible. In such scenarios, thenumber of dampers 20 would of course be reduced relative to designsincluding multiple flexures 18.

The flexures 47 are shown to be fastened to their mating components.They may instead be bonded as appropriate.

The flexures 18, 47 are shown to be U and rectangular shapedrespectively. Any suitable shape (e.g., I-shaped, L-shaped, O-shaped,etc.), however, may be used. To the extent there are more than one ofthe flexures 18, they need not have the same shape or thickness.Simulation and testing may reveal that different shaped or differentthickness (or both) flexures may have better performance than sameshaped/thickness flexures. For reference, the flexures 18 in the exampleof FIGS. 1, 2 and 3 are approximately 7 thousandths of an inch thick.Although different shaped/thickness flexures 47 are also contemplated,media tracking performance may limit the extent to which these flexurescan be different.

The spans of the flexures 18, 47 are shown to be different. That is, thedistance between the carriage 12 and mount 14 is less than the distancebetween the carriage 12 and carriage 42. These spans, however, can bethe same, or the distance between the carriage 12 and mount 14 can begreater than the distance between the carriage 12 and carriage 42 asdesign constraints dictate. Among other things, the spans may influencethe optimum shape/thickness of the flexures 18, 47.

The words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the disclosure andclaims. As previously described, the features of various embodiments maybe combined to form further embodiments that may not be explicitlydescribed or illustrated. While various embodiments may have beendescribed as providing advantages or being preferred over otherembodiments or prior art implementations with respect to one or moredesired characteristics, those of ordinary skill in the art recognizethat one or more features or characteristics may be compromised toachieve desired overall system attributes, which depend on the specificapplication and implementation. These attributes include, but are notlimited to cost, strength, durability, life cycle cost, marketability,appearance, packaging, size, serviceability, weight, manufacturability,ease of assembly, etc. As such, embodiments described as less desirablethan other embodiments or prior art implementations with respect to oneor more characteristics are not outside the scope of the disclosure andmay be desirable for particular applications.

What is claimed is:
 1. A recording head positioning assembly comprising:a front end assembly including an isolation mount; a head assemblyincluding a recording head; a travel carriage spaced away from the frontend assembly and head assembly; guiding flexures secured to the travelcarriage and head assembly and configured to facilitate relativemovement between the travel carriage and the head assembly; and one ormore isolation flexures sandwiched between the guiding flexures, securedto the travel carriage and front end assembly, and configured tofacilitate relative movement between the travel carriage and the frontend assembly.
 2. The recording head positioning assembly of claim 1,further comprising one or more dampers disposed between and compressedby the travel carriage and the one or more isolation flexures.
 3. Therecording head positioning assembly of claim 1, wherein the isolationmount defines a pair of legs and wherein the one or more isolationflexures are disposed at opposite ends of the legs.
 4. The recordinghead positioning assembly of claim 3, wherein each of the guidingflexures is disposed adjacent to one of the opposite ends of the legs.5. The recording head positioning assembly of claim 3, wherein bases ofthe one or more isolation flexures span between and are attached to thelegs.
 6. The recording head positioning assembly of claim 1, wherein theone or more isolation flexures are U-shaped.
 7. The recording headpositioning assembly of claim 1, wherein arms of the one or moreisolation flexures span between and are attached to the travel carriageand front end assembly.
 8. The recording head positioning assembly ofclaim 1, wherein the one or more isolation flexures include a pluralityof isolation flexures having different shapes.
 9. The recording headpositioning assembly of claim 1, wherein the one or more isolationflexures include a plurality of isolation flexures having differentthicknesses.
 10. An adjustment subassembly for a recording headpositioning assembly comprising: a front end assembly including anisolation mount; a travel carriage spaced away from the front endassembly; isolation flexures secured to the travel carriage and frontend assembly to facilitate relative movement between the travel carriageand front end assembly; and one or more dampers disposed between andcompressed by the travel carriage and the isolation flexures to limittravel of the isolation flexures.
 11. The adjustment subassembly ofclaim 10, wherein the isolation mount defines a pair of legs and whereinthe isolation flexures are disposed at opposite ends of the legs. 12.The adjustment subassembly claim 11, wherein bases of the isolationflexures span between and are attached to the legs.
 13. The adjustmentsubassembly of claim 10, wherein the isolation flexures have differentshapes or different thicknesses.
 14. The adjustment subassembly of claim10, wherein the isolation flexures are U-shaped.
 15. The adjustmentsubassembly of claim 10, wherein arms of the isolation flexures spanbetween and are attached to the travel carriage and front end assembly.16. A recording head positioning assembly comprising: a coarse travelcarriage secured to and spaced away from each of a front end assemblyand a head assembly via sandwiched guiding flexures and isolationflexures; and dampers sandwiched between the coarse travel carriage andisolation flexures.
 17. The recording head positioning assembly of claim16, wherein the isolation flexures are disposed between the guidingflexures.
 18. The recording head positioning assembly of claim 16,wherein the isolation flexures have a same shape.
 19. The recording headpositioning assembly of claim 16, wherein the isolation flexures have asame thickness.
 20. The recording head positioning assembly of claim 16,wherein the front end assembly includes an isolation mount and a voicecoil motor housing and coil assembly and wherein the head assemblyincludes a fine travel carriage, head carrier, and recording head.